package org.apache.hawq.pxf.plugins.jdbc; | |
/* | |
* Licensed to the Apache Software Foundation (ASF) under one | |
* or more contributor license agreements. See the NOTICE file | |
* distributed with this work for additional information | |
* regarding copyright ownership. The ASF licenses this file | |
* to you under the Apache License, Version 2.0 (the | |
* "License"); you may not use this file except in compliance | |
* with the License. You may obtain a copy of the License at | |
* | |
* http://www.apache.org/licenses/LICENSE-2.0 | |
* | |
* Unless required by applicable law or agreed to in writing, | |
* software distributed under the License is distributed on an | |
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY | |
* KIND, either express or implied. See the License for the | |
* specific language governing permissions and limitations | |
* under the License. | |
*/ | |
import org.apache.hawq.pxf.api.BasicFilter; | |
import org.apache.hawq.pxf.api.FilterParser; | |
import org.apache.hawq.pxf.api.LogicalFilter; | |
import java.util.Arrays; | |
import java.util.LinkedList; | |
import java.util.List; | |
import java.text.ParseException; | |
/** | |
* A filter builder. Uses a single {@link BasicFilter} or a {@link List} of {@link BasicFilter} objects. | |
* | |
* The subclass {@link WhereSQLBuilder} will use the result to generate WHERE statement. | |
*/ | |
public class JdbcFilterBuilder implements FilterParser.FilterBuilder { | |
/** | |
* Translates a filterString into a {@link BasicFilter} or a | |
* list of such filters. | |
* | |
* @param filterString the string representation of the filter | |
* @return a {@link BasicFilter} or a {@link List} of {@link BasicFilter}. | |
* @throws ParseException if parsing the filter failed or filter is not a basic filter or list of basic filters | |
*/ | |
public Object getFilterObject(String filterString) throws ParseException { | |
try { | |
FilterParser parser = new FilterParser(this); | |
Object result = parser.parse(filterString.getBytes(FilterParser.DEFAULT_CHARSET)); | |
if ( | |
!(result instanceof LogicalFilter) && | |
!(result instanceof BasicFilter) && | |
!(result instanceof List) | |
) { | |
throw new Exception("'" + filterString + "' could not be resolved to a filter"); | |
} | |
return result; | |
} | |
catch (Exception e) { | |
throw new ParseException(e.getMessage(), 0); | |
} | |
} | |
@Override | |
public Object build(FilterParser.LogicalOperation op, Object leftOperand, Object rightOperand) { | |
return handleLogicalOperation(op, leftOperand, rightOperand); | |
} | |
@Override | |
public Object build(FilterParser.LogicalOperation op, Object filter) { | |
return handleLogicalOperation(op, filter); | |
} | |
@Override | |
public Object build(FilterParser.Operation opId, Object leftOperand, | |
Object rightOperand) throws Exception { | |
// Assume column is on the left | |
return handleSimpleOperations( | |
opId, | |
(FilterParser.ColumnIndex) leftOperand, | |
(FilterParser.Constant) rightOperand | |
); | |
} | |
@Override | |
public Object build(FilterParser.Operation operation, Object operand) throws UnsupportedOperationException { | |
if ( | |
operation == FilterParser.Operation.HDOP_IS_NULL || | |
operation == FilterParser.Operation.HDOP_IS_NOT_NULL | |
) { | |
// Use null for the constant value of null comparison | |
return handleSimpleOperations(operation, (FilterParser.ColumnIndex) operand, null); | |
} | |
else { | |
throw new UnsupportedOperationException("Unsupported unary operation '" + operation + "'"); | |
} | |
} | |
/* | |
* Handles simple column-operator-constant expressions. | |
* Creates a special filter in the case the column is the row key column | |
*/ | |
private BasicFilter handleSimpleOperations(FilterParser.Operation opId, | |
FilterParser.ColumnIndex column, | |
FilterParser.Constant constant) { | |
return new BasicFilter(opId, column, constant); | |
} | |
/** | |
* Handles AND of already calculated expressions. | |
* | |
* Four cases here: | |
* <ol> | |
* <li>both are simple filters</li> | |
* <li>left is a FilterList and right is a filter</li> | |
* <li>left is a filter and right is a FilterList</li> | |
* <li>both are FilterLists</li> | |
* </ol> | |
* Currently, 1, 2 can occur, since no parenthesis are used | |
* | |
* @param left left hand filter | |
* @param right right hand filter | |
* @return list of filters constructing the filter tree | |
*/ | |
private List<BasicFilter> handleCompoundOperations(List<BasicFilter> left, | |
BasicFilter right) { | |
left.add(right); | |
return left; | |
} | |
private List<BasicFilter> handleCompoundOperations(BasicFilter left, | |
BasicFilter right) { | |
List<BasicFilter> result = new LinkedList<>(); | |
result.add(left); | |
result.add(right); | |
return result; | |
} | |
private Object handleLogicalOperation(FilterParser.LogicalOperation operator, Object leftOperand, Object rightOperand) { | |
List<Object> result = new LinkedList<>(); | |
result.add(leftOperand); | |
result.add(rightOperand); | |
return new LogicalFilter(operator, result); | |
} | |
private Object handleLogicalOperation(FilterParser.LogicalOperation operator, Object filter) { | |
return new LogicalFilter(operator, Arrays.asList(filter)); | |
} | |
} |